This is a continuation application of a longitudinal study to determine the effects of systemic hypertension on the rate of progression of diabetic retinopathy and related changes in renal function and neurologic findings in the study population. The proposed renewal is designed to accumulate the additional information necessary to identify with certainty the correlations between elevated blood pressure, altered behavior of the renin-angiotensin-aldosterone system and the severity and progression of diabetic retinopathy and alteration in renal function. The data collected during the study include careful sequential histotrical data and repeated physical examinations, blood studies to characterize the behavior of renin, prorenin, aldosterone, angiotensin II, sodium excretion and changes in blood glucose, uric acid, triglycerides and cholesterol. Patients are seen at intervals of every six months and studies include careful blood pressure recordings in the supine, sitting and standing position, sequential stereo retinal photographs as well as extensive and standardized complete ophthalmologic examination. The retinal photographs are read independently by two of the investigators who are completely masked from the patient's identity and study data.